a gage for grooves

by John Bokstrom

Grooved planes already have several advantages over the usual flat-soled planes. This gage gives you one more-that of being able to check a finished strip more quickly and accurately than any other method. (1)

The gage for grooves. Note the grooves on the underside of the base

To make this device you need the following:

1. a dial gage for thickness applications, the type that reads from 0 to 100 as the spindle moves up into the case. A revolution counter is not necessary.

2. a flat contact point for the spindle. Check this carefully to ensure the contact surface is exactly square to the spindle.

3. a base, which you may be able to make. If not, buy a two-inch base of the type used with depth indicators. In either case, the bottom surface of the base requires that two grooves, as in figures 1 and 2, be filed or ground across it. The first is the width (3/8") of the hole for the stem and approximately 3/16" deep. The second is the same width as the groove in your plane and .005" to .010" deep. With this wider groove the base presents the same footprint as your plane and compensates for many imperfections in your form.

Matching grooves in plane and gage. (2)

A little more about this particular plane: while it is capable of being set as fine as desired for the finish planing of strips, it is easier and requires less work when carefully adjusted to make a shaving of exactly .002". At this setting, when a strip is planed to completion, it extends above the form by exactly .002" everywhere along its length. In this case the form is set .002" tight to get the desired finished dimension. These numbers for your plane may not be exactly the same-you'll have to find them by testing.

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(1) See elsewhere on this website for instructions on "grooving" a plane.

(2) Note, this plane is fitted with a plane leveler, also known as "training wheels".